Online Interior Design and Decoration Courses. Rhodec International was founded in 1960 as a private, independent institution to cater to the increasing educational needs of the burgeoning Interior Design profession around the world. Our world-renowned interior design course study programmes were carefully designed by leading professionals to offer a sensible and stimulating alternative for the training of an Interior Designer. We offer the most thorough home study interior design course that is available anywhere in the world. Although some full-time schools run interior design correspondence courses as a side-line, we have specialized for fifty years in teaching Interior Design solely by the home study method, and our courses are specifically tailored to suit busy individuals who cannot give up work and domestic commitments to attend full time courses and lectures.